Zergling
The Zergling is a Groud Attacking Merc only, it is the cheapest of all the mercs and can be surprisingly Effective in Late game play. the zergling specializes in Very fast attacks and movement speed. When upgraded with Razor Claws from the merc building in the bottom center of the arena, the zerglings attack faster, gain armor and do extra damage to armored units in exchange for a decrease in the base damage. The zerglings were weakest against Helions ( even more so if they have pyrite ignitor ) but as of 1.0s release the Firebat is the new flamethrower in town and is the one ot avoid, and early on get taken out by almost every other merc without too much trouble. They are strongest against un-upgraded or minimally upgraded marines, and are almost unstoppable when up against armored units when they have full razor claws + other upgrades. 'Some basic Strategy for Zergling play' Early Pressure: If you start the game with zerglings your best path for early pressure is to get the Attack speed upgrade before the movement speed upgrade. Early in the game most other players will get Marauders, though some do get lings and zealots. first off scout with 1 ling running into each base. try and find a player who has opted to not get mercs just yet and attack them first with about 15 lings. keep up this pressure on that player till they either get mercs or upgrade their rines to do enough to your lings to where your attacks become ineffective. after getting the attack speed upgrade first, get the movement speed upgrade after that. once you have both of those continue checking what mercs the other players have, if a lot of players have gone armored units you want to get Razor claws as soon as possible. once you have razor claw upgrades coming ( max of 3 is allowed ) you can start doing heavy damage to players with armored mercs, at this point your lings are most effective against normal Stalkers ( avoid lancers if possible ),marauders, and roaches. but roaches do heavy damage back to lings so avoid these if possible still. Zealots are still a threat to your lings and so are helions until the late game. Avoid upgrading to cracklings quickly otherwise you risk "feeding" your opponents. while cracklings are more effective they also triple the bounty of the lings thus giving your opponents more for killing them. by the time you have max razor claws ( you should also have 4-5 merc weapon upgrades and some 2-3 merc health upgrades ) it is a good time to get cracklings,normally this time occurse around the 25-30 minute mark, sometimes sooner if your early pressure racks in some serious cash. at this point your lings are beast and in large numbers will chew through almost any force. make sure you snipe out merc buildings that are left unprotected because remember your lings do crazy damage to armored units and have a crazy fast attack speed. GOOD LUCK!